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Discussion Starter #41
So I just went out to try tracing that wire and I forgot which one it was so I tested try testing it and I didn't have any power through either one of the ground wires and then I realized I didn't have the ecm plugged in so I plugged that back in and tested the wires again still no power in the ground wires so I hooked the noid lights up and now I've got pulses injectors are spraying as well but didn't start pretty sure it's because that battery was basically dead so it's on the charger right now gonne be trying it again in 10 minutes to see what happens.
So I had the battery disconnected as well as the ecm for a day or so

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Discussion Starter #42
Okay so now it's definitely getting fuel and when I turn it over it fires and sounds like it's about to fire to life but once I let go of the key it will spit and sputter for 15 seconds then die.
But with starting fluid it starts and runs fine till the fumes are gone

Bad fuel? Bad spark plugs?

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If it runs fine on starting fluid, the plugs and ignition are good.
You have a fuel problem.
Bad fuel, no pressure, injector problem.
 

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Bad fuel? Bad spark plugs?
Sorry, I wrote this last night but forgot to hit the "Post reply" button. X2 on what @RayVoy said.

Or ignition switch? How's your fuel pressure with key on not running and then key on after starting? Maybe your alternator isn't charging and your battery is too weak, IDK. Just throwing it out there. I'm still wondering how, all of a sudden, you started getting the injectors working - PFM? There's still a chance your ECM is wigging out.
 

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Discussion Starter #45
Thank you never had the issue so didn't know how to go about it. And as for the fuel problem injectors are spraying when I try starting and come out and look the walls of the tbi are wet as well as a little puddle of gas. I have yet to see how it sprays

I will get the loan tool to check pressure again but I don't think it has changed.

How would I go about getting a ecm? Used new I can't afford to go buy one from a dealer

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At this point, I wouldn't go out and buy a new/used computer

Tell me about the gas (you may have discussed it earlier; but I didn't go back and re-read the thread), was the gas in the truck when you bought it, or have you added it?

We know starting fluid works and it runs fine.
So, get a little bit of new gas and a dollar store spray bottle.
Spray some new gas into the TBI and see if it runs.
It should run as it did on starting fluid.
Ok, pour the new gas out of the spray bottle and replace it with gas from the tank, go to the bottom of the tank, that's where the water will be.
Spray some of this gas into the TBI and report back.
 

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I just recently purchased a 1990 Chevy 2500 single cab long bed with the 350 tbi that has been D.O.T inspected until 2018 in MN.
The issue - it has a fuel delivery problem and the previous owner was fairly certain that it needed a fuel pump and I wasnt surprised cuz ive had to do that with past 90s gm trucks.

It ran long enough to drive up on the trailer while under its own power and it also drove off the trailer on its own power(not that same day I brought home) but you did have to keep foot on throttle otherwise it would stall out and not start again until the next day.

Just remembered I had realised that the fuel injectors were not spraying they click with a 9v battery but don't spray fuel
So it's been about a week since I got it home and this is what I have replaced so far-
1. New Fuel pump
2. New Fuel filter
3. New Fuel pump relay
4. New Fuel pressure regulator
5. Used fuel injector wire connecters
6. Used fuel injectors (from junkyard may not be in working condition)
7. Used distributor stem with used cap and rotor and pick up coil or whatever the name is of the third part on the distributor
Fuel pressure in line is good

that's what I've done so far in that order
The motor runs on starting fluid or when you dribble fuel in the carb motor runs fine I removed injectors for first time to try cleaning them and didn't install them correctly and fuel bubbled out on top of the injectors and the truck started to fire but didn't get enough fuel from that to start it fully
I've read mixed things on similar issues the forums that we're almost identical were never finished or they got way off track with others jumping in with different year and models

Thanks in advance for any help. I'm no wire wiz hate messing with electrical

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I just recently purchased a 1990 Chevy 2500 single cab long bed with the 350 tbi that has been D.O.T inspected until 2018 in MN.
The issue - it has a fuel delivery problem and the previous owner was fairly certain that it needed a fuel pump and I wasnt surprised cuz ive had to do that with past 90s gm trucks.

It ran long enough to drive up on the trailer while under its own power and it also drove off the trailer on its own power(not that same day I brought home) but you did have to keep foot on throttle otherwise it would stall out and not start again until the next day.

Just remembered I had realised that the fuel injectors were not spraying they click with a 9v battery but don't spray fuel
So it's been about a week since I got it home and this is what I have replaced so far-
1. New Fuel pump
2. New Fuel filter
3. New Fuel pump relay
4. New Fuel pressure regulator
5. Used fuel injector wire connecters
6. Used fuel injectors (from junkyard may not be in working condition)
7. Used distributor stem with used cap and rotor and pick up coil or whatever the name is of the third part on the distributor
Fuel pressure in line is good

that's what I've done so far in that order
The motor runs on starting fluid or when you dribble fuel in the carb motor runs fine I removed injectors for first time to try cleaning them and didn't install them correctly and fuel bubbled out on top of the injectors and the truck started to fire but didn't get enough fuel from that to start it fully
I've read mixed things on similar issues the forums that we're almost identical were never finished or they got way off track with others jumping in with different year and models

Thanks in advance for any help. I'm no wire wiz hate messing with electrical

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I have a 1991 GMC K1500 350. I had the same troubles you describe. After about ten minutes run time, it was a random dying of the truck with no restart until about an hour or so later. Replace and checked everything you have listed. All the experts standing around had so many thoughts I couldn't listen any more. Looking through an old manual, this caught my eye. Ignition control module, be sure there is plenty of dielectric grease on the bottom when mounted. This triggered the thought, exactly the problem...HEAT.
Went to ORieleys bought an ignition control module for $40. It comes with the grease too. Installed in about ten minutes. The truck has been running perfectly since. The old module had no grease on it and looked overheated in condition too. It's not just the grease in this situation but a contributing factor.By the way it is mounted to the driver side of the distributor, held on by two screws. Remove the cap and move some things around to get to it easily.
I hope this information helps. Again my truck has had absolutely no problems since, about 5 months now.Good luck.
 

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@[email protected] It is not dielectric grease, it's thermal paste - big difference! If you do buy an ICM, don't get cheap junk like Pertronix (mine died in less than 2000 miles) or Spectra Premium, get AC Delco or Delphi. They do come with the thermal paste (for heat transfer) but I use this stuff. When applying the paste keep the screw holes clean for a good ground connection.

 

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Discussion Starter #49
I tried that gas thing it started with the fresh gas I wasn't able to get any from the tank it is pretty low but I just got done adding 8 fresh gallons of gas to the tank

And let's say it is fuel pressure I really don't think it is but just wanna know what you guys think I should look for??
it's got a brand new fuel pump assembly brand new fuel filter brand new fuel pump relay and brand new fuel pressure regulator

And I messed with the truck today I can start it and it will run for 10 seconds and shut off and I can't try repeatedly to start it I have to give it about a minute in between each try and when it's running for those short seconds I've tried pumping the peddle and it will start to rev up but then just die
I really think it's running rich until it starts then it acts like it cuts off spark because I can see it still give fuel before it dies


Also Its been on the battery charger whenever I've messed with it

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When it dies and if you still have the key on, does the security light flash?
 

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Discussion Starter #51
No nothing flashes including check engine/ service engine soon light and there's also no codes

I've read on some forums about the oil pressure sensor causing no start
Would that cause it to start and if it's bad or senses no oil pressure it would shut off power to the fuel pump?
 

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@[email protected] It is not dielectric grease, it's thermal paste - big difference! If you do buy an ICM, don't get cheap junk like Pertronix (mine died in less than 2000 miles) or Spectra Premium, get AC Delco or Delphi. They do come with the thermal paste (for heat transfer) but I use this stuff. When applying the paste keep the screw holes clean for a good ground connection.

Going back to the manual that originally gave me the idea of checking this component and condition,chapter 5 Engine electrical systems,section 7 Ignition module-replacement step 7 clearly reads: Be sure to apply the silicone dielectric grease supplied with the new module to the bottom of the ignition module. DO NOT use any other type of grease! If the grease isn't used, the module will overheat and destroy itself. So I did exactly this and the result has been the problem eliminated and the truck now running fantastic. Years ago and probably still today, this same grease was used in computers between the processor and the heat sink for the same reason., removal of heat.
 

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Dielectric grease is insulating grease. You must use the conductive paste to draw the heat out of the ICM and onto the big aluminum block on the bottom so it can dissipate the heat. Dielectric grease is not used for this purpose. It’s purpose is to insulate and prevent moisture infiltration on electrical connections.
You’re absolutely correct. The grease that comes with the module must be used. It will absolutely fail prematurely without it.

Oil pressure switch will not prevent a TBI engine from starting. The only thing the oil switch does is give the engine another path to give power to the fuel pump circuit. In the event the fuel relay fails, the oil pressure switch will keep the fuel pump online.

Also, there is no security/pass lock feature with the ‘90 model. That started in ‘96.
 
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Ok, everyone sit back and take a deep breath, your over thinking this problem.

If it fires and runs when fresh gas, or either, is sprayed into the throttle body, it is a fuel delivery problem, nothing more.

It is that simple, a clean fuel delivery problem.

I asked about the lights to be sure the security system wasn't to blame. No flashing security lights, the security system shouldn't be causing the problem.

You have a few things that need to be in place:
You need to be sure the fuel in the tank is good, clean and fresh,
You need clear unrestricted lines to flow the fuel to the engine.
You need good fuel pressure
And, you need injectors that open (fire) correctly.

Find which of those is broken and you have found the problem.
 

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Discussion Starter #55
Finally got to test fuel pressure again this time it reads like 4 psi. The very first time I turned the key it was like right at 10 but then fuel started leaking everywhere so I went back under and tightened everything and then it started reading between 0-4

Once again replaced:
New whole Fuel pump assembly
New fuel filter
New fuel pump relay
New fuel pressure regulator
In the fuel system

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The very first time I turned the key it was like right at 10 but then fuel started leaking everywhere
I don't remember, did you rebuild the TB including the injectors' screens and O-rings? When you put it back together you need to place the big (top) O-ring and metal backer in the housing, then slide the injectors in. If you don't you'll pinch the O-ring and it'll leak all over. BTW - 10PSI is low IMHO, s/b at least 11.
 

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And what was the pressure after changing the items on your list?
 

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Discussion Starter #58
Yes I placed both metal and oring back in and no they didn't get pinched
And when I first started this thread I had 10-13psi

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And did it start?
 
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